You will probably find that a small number of studentships are available in this area each year. However competition will be extremely intense for such a popular subject area. Most studentships starting in October 2004 are not yet advertised.
A self funded PhD is not cheap. On top of the £3000 university fees, you will need to cover research expences, such as field work (flights, food, accomodation etc). If you're lucky the supervisor may be able to get some of these costs covered for you. To get accepted you will still need to show that you have the ability to complete a PhD. Even though you're paying the bill, the supervisor will be the one in charge.
Use the internet to find labs working in the area you're interested in and write to them explaining that you'd like to fund yourself. Some of the following may be good places to start: Primate Society of Great Britain, The Primate Information Network or The Leaky Foundation